Propeller



E. BOENING PROPELLER Filed March 17. 1925 lNVENTOR 21%: ZOE/WW6 v BY W.WK' 7 05 ATTORNEYS Patented Aug. 24, 1926.

UNITED STATES ERNEST BOENING, OF YONKERS, NEW YORK.

PROPELLER.

Application filed March. 17, 1925.

My invention relates to propellers, particularly such as are adapted to operate in the water, although the improved construction may be used for propellers working in the air, and may also be employed for the generation of power from a stream or from air currents. The object of the invention is to improve the efliciency by reducing losses, particularly those due to the radial outward movement of the fluid under the influence of centrifugal force.

\Vithout desiring to restrict myself to the details illustrated, I will now, describe a preferred and satisfactory embodiment of my invention with reference to the acconipanying drawings, in which Fig. 1 is a rear elevation of a ships propeller constructed according to my improved design; Fig. 2 is a side elevation thereof; and Fig.

3 is a partial section on the line 3-3 of Fig. 1.

The axis about which the propeller rotates is indicated at 10, and in the particular construction shown, the propeller has three blades, all rotating in the same plane or path, but it will be understood that I do not restrict myself to this particular arrangement or number of blades.

Each of the blades is of a twisted or screw shape to obtain a propelling action of the Well-known character. The body 11 of the blade is narrowest at the hub 12 to which the blades are secured, or with which they are integral. The hub has a hole 13 to receive the propeller shaft (not shown) and agroove 14 for the reception of a key (not shown) to connect the shaft rigidly with said hub. The blades are widest at their outer edges or tips, the side edges 15, 16 of the same blade therefor diverging outwardly to the tip. Preferably the leading edge 15 (that is, the edge which cuts the water When the ship is being propelled ahead) is convex from hub to tip, while the following 4- edge 16 is convex only at its outer portion and concave at its inner portion.

The tip of each blade is bent toward the rear as indicated at 17, to form a barrier preventing the outward movement and cscape of the water or other fluid. To accomplish this, the bend 17 should have its inner surface (the one directed toward the hub) extended at least to a point (indicated at 18 in Fig. 3) where such surface is perpendicular to a plane of rotation, or in other words, perpendicular to a plane which is Serial No. 16,147.

itself perpendicular to the axis 10. Preferably, however, the bend is extended inwardly beyond this point 18, as shown, so as to form a flange or lip 19 directed in wardly and defining, in conjunction with the body llof the blade, a pocket 20 from which the water or other fluid can escape only at the open ends, as will be evident from Figs. 1 and 2. Lines drawn on the bend 17 and on the lip or flange 19 lengthwise of the pocket 20 are preferably straight, as will appear from the straight transverse lines bounding the blade tips in Fig. 1, said transverse lines being approximately perpendicular to the radial center lines of the re spective blades.

The marked increase in efliciency obtained bv the use of my improved propeller has been demonstrated convincingly by comparative tests. The barrier interposed by the bend 17 to the direct or radial outward escape of the water or other fluid is the main factor in securing this advantage, and when the flange or lip 19 is provided to form the pocket 20, the restraining effect of the blade tip on the tendency of the fluid to escape in a radial outward direction is increased very materially. Actual tests have shown that, under the same conditions, my propeller will increase the speed of a boat very materially above the speed obtained with propellers of standard makes heretofore considered the best on the market.

Various modificationsmay be made Without departing from the nature of my invention as set forth in the appended claims.

With the new propeller, the boat will hold her course readily even at low speeds, and in the docking or warping of large steamers, the tugs usually employed will either be dispensed with entirely, or at least a smaller number of tugs will suflice.

I claim:

1. A structure adapted for use as a propeller, comprising a central body or hub and a plurality of blades extending outwardly therefrom, each of said blades having a convex leading edge and a following edge convex at its outer portion and concave at its inner portion, said blade being widest at its tip, and contracted toward the hub, and being provided,at such tip, with a bend extending on the side which forms the active face of the blade, to form a barrier to the radial outward movement of the fluid, the outer edge of said tip being substantially straight, and the bend of the tip being formed with a flange extending inwardly toward said central body or hub and forming with said active surface of the blade, a transverse pocket or channel substantially straight in the direction of its length.

2. A structure adapted for use as a pro peller, comprising a central body or hub and a plurality of blades extending outwardly therefrom, each of said blades increasing in width outwardly and being provided, at its tip, with a bend extending on the side which forms the active face of the blade, to form a barrier to the radial outward movement of the fluid, the outer edge of said tip being substantially straight, and the bend of the tip being formed with a flange extending inwardly toward said central body or hub and forming with said active surface of the blade, a transverse pocket or channel substantially straight in the direction of its length.

3. A structure adapted for use as a propeller, comprising a central body or hub and a plurality of blades extending outwardly therefrom, each of said blades increasing in Width outwardly and being provided, at its tip, with a bend extending on the side which forms the active face of the blade, to form a barrier to the radial outward movement of the fluid, the said bend being formed with a flange extending inwardly toward said (entral body or hub and forming with said active surface of the blade, a pocket or channel ranging transversely of said blade.

In testimony whereof I have hereunto set my hand.

ERNEST BOENING. 

